WE are asking the nation to pray that doctors I scanning Wayne Rooney's foot find plenty of "recalcification".

No, it's not a word you come across often, but our World Cup hopes rest on there being loads of the stuff around the striker's fractured metatarsal.

If there is, it's a good sign the cracked bone is healing properly and he'll be on the plane back to Germany. If not, then his dream - and maybe even ours - is over.

One source said: "His whole summer is resting on whether there is enough recalcification.

"There is a specific measurement that needs to be reached if Wayne is to return to Germany. It's like the magic number."

The 20-year-old has been told privately that if he is not going to be fit until the quarter finals start on June 30, he will not be rejoining the squad.

But he will fly back to Germany if there is a "reasonable" chance of him playing in the second round of the competition starting June 24.

Roo is due in Manchester today for an MRI scan this afternoon which will take around 30 minutes.

Doctors should have results later this evening and the nation will breathe a huge sigh of relief if recalcification is in abundance.

But what exactly is this recalcification? Specialist Clifton Bradeley, a former Great Britain athlete, said: "It is evidence that the bones are uniting.

"Doctors will be hoping to see lots of cellular activity at bone level, effectively putting a natural plaster around the injury.

"That is what is meant by recalcification. Without that, and if all that the scan shows is virgin bone, there is a huge risk of another fracture if there is any contact to the joint.

"On the other hand, if the growth is good and there is evidence that the density of the bone is high, that will be very positive.

"Hopefully there will be no signs of the fracture itself. If Rooney is going to be able to play in the World Cup they will not see the fracture any more.

"Unlike a normal X-ray, which just looks at the bone, the MRI scan shows the structure of the foot, the soft tissue, muscles and ligaments as well as the scar tissue, in a three-dimensional image that looks likes it's been through a bacon slicer. What the MRI scan will show is what's called signal, basically inflammation. Specialists will be looking for a low signal.

"Wayne has undergone the accelerated healing therapy and he is a young, healthy guy.

"He wants to be there and that is important, because the power can play a big part in recovering from injuries." Fans have been boosted by pictures of Rooney running with a ball in training.

But there were a couple of worrying signs as he went through gruelling sessions at the team's camp in Baden-Baden. At one point the strain of the injury showed as he shook his injured foot straight after a simple kick of the ball. And he was even spotted wincing when he belted a long ball.

Three doctors - from FIFA, the FA and Manchester United - will make the final call on Rooney's summer.

If he is not fit, Tottenham striker Jermain Defoe will replace him.

But an announcement may not be made until tomorrow morning. The deadline for a decision on whether to replace Rooney is Friday at 2pm, 24 hours before England's opening game against Paraguay.

One thing's for sure, by tomorrow we'll all finally know whether Roo will be playing any part in the World Cup, which starts on Friday.

And we all know now what recalcification means. Who says football isn't educational?